I suggest a popup window integrated in PLAY to give information about keyswitch and velocity switch articulations for each instrument, instead of going back to the manual every time you need some information.

Also I see the articulation window in Play is quite small, and if you have a lot of articulations for one instrument, navigating up and down is difficult. I suggest some change to make it easier like making a separate window for the articulations.

and finally changing the view of play between browser, player etc.. I think much better if it is a tab rather than a button